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Rabbits in Urban Agriculture
Although it is not a culturally popular practice in the United States, as it is in many European countries, raising rabbits is an ideal meat-producing supplement to many urban farms for a variety of reasons. If one is not comfortable eating rabbit meat, certain rabbit breeds may also be raised for the production of wool, although this is less efficient or profitable than rabbits raised for meat. Rabbits have a small body size, making them easier to keep in space-limited urban locations. Their notoriously short generation interval and high reproductive potential make even a small farm fairly productive. Rabbits also have a very rapid growth rate, allowing them to acquire mass and be sold or consumed in a short period of time. There are a number of rabbit breeds that are suitable for urban agriculture, allowing each operation to have considerable genetic diversity and thus be more resistant to disease or harsh conditions. Rabbits can consume forages and by-products as major diet components, meaning that they are not in direct competition with humans for food3. If the owner of the rabbits also has a garden or urban farm, the plant material that is not suitable for human consumption can be used as feed for the rabbits, enhancing the economic and ecological efficiency of the operation as a whole3. Rabbits are also much quieter, easier to butcher, and have a less offensive scent than other animals such as chickens , cows, or pigs 3. Additionally, rabbits have a very high feed conversion ratio (FCR), a measurement of the grams of food required to produce one gram of the animal. A feed conversion ratio of 3.0, meaning that one gram of rabbit can be produced with only three grams of food, can be achieved5. This is far better than that of pigs, cows or sheep, and is similar to the FCR of chickens and turkeys. Remarkably, however, rabbits are able to achieve this efficiency while converting proteins in low quality plant foods that many animals, including chickens and turkeys, are unable to eat1. Lastly, raising rabbits in the upper Midwest is optimal, as one of the major drawbacks is that rabbit growth and survival drop suddenly at temperatures higher than 86 degrees Fahrenheit3. While even the northernmost regions of the United States reach this temperature at the height of summer, it is typically a rather brief period. This makes the Midwest the optimal climate for incorporating rabbits into urban farms. Care Rabbits are typically kept outdoors in small cages, often referred to as hutches. Many operations keep five to six rabbits in a single cage, although there is evidence that sharing a cage with fewer individuals may lead to increased production5. Food and water must be provided daily, and rabbits raised for wool production require grooming. Food can consist simply of plant fodder that is inedible to humans, including grasses, vines, leaves, or other plant materials. This diet, however, will not lead to optimal production rates. Plant material from legumes is better feed than grasses due to their increased nitrogen content, although legumes are slightly worse than a processed cereal bran3. Feeding generally accounts for 60-70% of the total cost of the operation, although this cost could obviously be reduced if a large portion of the feed was produced on site by a diversified urban farm5. This reduction in cost is another reason that raising rabbits would be a sensible addition to many urban agricultural efforts. Rabbits are usually sold at a market or slaughtered when they reach a weight of about 4.5 lbs (2 kg), unless the individual is a doe used for breeding in the operation. Fertilizer The feces of rabbits also functions as an excellent fertilizer for gardens or small urban farms. Rabbit manure fertilizer has been shown to be more effective than commercial NPK fertilizer in increasing tomato production6. For tomatoes, optimal conditions were at a spread of 3.34 lbs per square yard, although most practical applications will be much smaller than that. Rabbit manure is a less effective fertilizer than chicken or pig manure, equally as effective as human manure, and better than cow manure6. However, for reasons mentioned above, rabbits may be a more sensible option in an urban setting than chickens or pigs, and the manure produced is still of a very high quality. Meat Production Consumption/Dietary Facts While rabbit meat is not culturally popular in the United States and the average American consumes only 5 ounces of rabbit meat per year, Italians consume over 12.5 pounds per person annually1. Rabbit meat is an excellent dietary replacement for chicken, beef, or pork, and contains less stearic and oleic fatty acids than other animals typically consumed in the American diet. It also has a higher proportion of the essential polyunsaturated linolenic and linoleic fatty acids. Additionally, rabbit is higher in calcium and phosphorous and slightly higher in protein content, while lower in total fat and sodium when compared to beef, pork, chicken , and mutton1. A cooked rabbit carcass will typically maintain 55-58% of the live weight of the animal, and a 4.5 lb rabbit will contain roughly 40-100 grams of fat, dependent on the breed of rabbit and diet, and about 3.5 ounces of edible organs 1. Efficiency Rabbits are known for being a highly efficient animal to raise for meat in terms of the amount of growth that occurs per pound of food provided. Despite consuming low-quality food sources that would not be suitable to other animals, rabbits can transform 20% of the proteins that they eat into edible meat proteins. Comparable figures for other species are 22-23% for broiler chickens, 16-18% for pigs, and 8-12% for cows1. While a food conversion ratio (FCR), which describes the grams of food needed to produce one gram of animal body weight, below 3.0 has been described for rabbits in highly commercialized farms, an FCR of 6.9 is to be expected for rabbits eating a diet composed entirely of vegetation not edible for humans, including leaves, grass, and stems among other things1. However, the FCR can be reduced to about 3.9 by simply changing 30% of the diet to higher nutrient food, such as corn or other human food waste. Optimization of the operation can lead to an FCR of 3.0 even for small urban farms, and there are many opportunities for optimization5. First, a highly efficient breed can be selected. The New Zealand White breed is very commonly used in rabbit meat production, but the Gray Giant breed has been found to have a lower mortality rate, a faster rate of weight gain, and a lower FCR, suggesting that this may be an ideal breed for optimizing a farm for meat production4. Supplementing the diet with 2-3% oils or fats during the period when the rabbits are 30-65 days of age, known as the fattening stage, can reduce the FRC by up to 0.155. Raising each rabbit in an individual cage rather than in the more typical group cages of 3-6 rabbits can decrease the FCR by an additional 11.8%5. Lastly, slaughtering at a lower weight (younger age) can reduce the overall FCR, as the FCR steadily increases as the rabbits become older and become less efficient in converting their food into additional body weight5. Achieving the lowest FCR possible is important for running a highly efficient operation, so farmers should consider all of these options when planning their farm. Tradeoffs that reduce sustainability, such as supplementing the diet with higher quality foods, must also be considered. To maximize the resource use efficiency in an urban farm, accepting a higher FCR while feeding the rabbits exclusively byproducts from the garden may be a more appealing option. Productivity The production expectations for each operation will vary depending on the location and size of the operation, but some figures should remain fairly consistent across small, devoted farms. For a devoted rabbit farm of under 100 does of no particular breed, the following productivity would be considered normal. Each doe will produce roughly 20-25 offspring per year, with a period of about 90-100 days between litters. The size of your operation will be dependent largely on the amount of time you are willing to invest in caring for the rabbits. Expect to spend 16 working hours per doe each year, which should result in an average of 13 working minutes per pound of carcass1. The offspring from each doe should be expected to grow at a combined rate of 107 pounds of live weight per year, or 1.1 pounds of dressed meat per week2. Thus, a small operation consisting of 3-5 breeding does could produce 3-5 pounds of meat per week. Rabbits from commercial operations in the United States reach market weight (4.5 lbs) in 2-2.5 months, while rabbits from small operations in Latin America and Asia reach this weight in an average of 3.2 months3. Urban farms in the Midwest should expect their rabbits to reach market weight somewhere in between these two conditions. The production cost of rabbit meat is 25-35% higher than the costs of producing the same quantity of meat in pigs in a rural setting, but pig farming in an urban setting is difficult, so rabbit production is likely a much more effective option for urban farmers in the upper Midwest5. Wool Production In addition to being an efficient producer of meat, rabbits can also be raised for their production of wool. A select number of special breeds of rabbit, known commonly as Angora rabbits, grow long, high-quality wool known as Angora wool. Angora wool costs 40-50 times the price of so-called greasy wool from sheep and other animals1. While each individual rabbit and each breed is different, the wool of a typical Angora rabbit grows at a rate of 0.69 millimeters per day7, adding up to 249 grams every 14 weeks, or approximately 2 lbs per year8. At a price of $10 per ounce, each rabbit can generate an average of $320 of wool each year. Rabbits molt four times each year, and molding is often an optimal time to harvest the wool7. There are three methods for harvesting the wool: plucking it out by hand, shearing the rabbit with an electric shaver, or clipping the wool with scissors. All three methods produce the same amount of total wool, but they also have costs and benefits7. Plucking produces the highest proportion of No. 1 wool, the wool that is the highest quality and worth the highest price7. However, plucking is much slower and more tedious than the other methods. Shearing is the fastest method for commercial production, but produces the lowest quality wool8. Clipping could be thought of as a middle ground between these two, although more similar to shearing than to plucking. A common problem with Angora rabbits, observed in roughly 10% of individuals regardless of breed, is the matting of the valuable wool, which dramatically reduces its quality. Matting is most common in males, which leads many farmers to prefer keeping primarily females for wool production, although long-term studies have shown that there are no significant differences in quality wool production between males and females7. Matting is also more common in warm weather, which is a potential advantage of urban farms in the upper Midwest, where warm temperatures are fairly infrequent. Matting can also be avoided by harvesting the wool at shorter intervals, such as every 10 weeks, instead of at the time of molting. This may be something to consider if matting is becoming a serious problem for your operation. Plucking has also been suggested as the best method for wool collection for the long-term health of the coat, although this claim is only loosely based in evidence7. Larger rabbits generate a larger yield of wool, but are not necessarily more efficient than smaller rabbits when considering the financial investment of the farmer. The best indicator of efficiency is the amount of wool produced per body weight of the rabbit. An ambitious farmer could collect this information for individuals on their farm and breed the most exceptional individuals in hopes of increasing the efficiency of the operation7. In commercial settings, rabbits are often butchered and sold for meat after the 3rd harvest of wool. While Angora rabbits are not as efficient at producing meat as other breeds with shorter fur, this can be a supplementary source of income to a wool-producing operation. In such operations, 55-70% of the income is generated by the wool, with 30-45% coming from the meat that is sold1. Citations 1. Coudert, P., R. Rouvier, and H. De Rochambeau. The rabbit: husbandry, health, and production. Rome: Food and Agriculture organization of the United Nations, 1986. 2. Lukefahr, S. D., and P. R. Cheeke. "Rabbit project development strategies in subsistence farming systems."World Anim. Rev 69.4 (1991). 3. Cheeke, P. R. "Potentials of rabbit production in tropical and subtropical agricultural systems." Journal of Animal Science 63.5 (1986): 1581-1586. 4. Dhara, K. C., et al. "A Study on Performance of New Zealand White and Gray Giant Broiler Rabbits." VetScan 4.2 (2009). 5. Maertens, L. "Possibilities to reduce the feed conversion in rabbit production."Proc.: Giornate di Coniglicoltura ASIC 2-3 April 2009, Forlì, Italy. 1 10 (2009). 6. Oikeh, S. O., and J. E. Asiegbu. "Growth and yield responses of tomatoes to sources and rates of organic manures in ferralitic soils." Bioresource technology ''45.1 (1993): 21-25. 7. Hardy, Thora Marggraff Plitt, and Ethel H. Dolnick. ''Angora Rabbit Wool Production. Washington, D.C.: U.S. Dept. of Agriculture, 1948. 8. Rochambeau, H. de, R. G. Thébault, and J. Grun. "Angora rabbit wool production: non-genetic factors affecting quantity and quality of wool." Anim. Prod 52 (1991): 383-393.